This project will harness the power of Drosophila genetics to complete a genome-wide analysis of the mechanisms controlling toxicity of AxD-linked mutant human GFAP to glia. New, comprehensive collections of transgenic RNAi lines will be crossed to the Drosophila model of AxD. Rigorous validation studies will confirm the identities of modifier genes. Candidate genes and pathways will then be prioritized for detailed mechanistic analysis in close collaboration with other members of the Program Project. We will also confirm and extend preliminary data we have developed implicating NO as a secreted signal that promotes neuronal death. Specifically, we will use a new expression system we have developed to test the hypothesis that glia release NO, which then activates cell death pathways in neurons through cGMP-dependent pathways. These studies are expected to significantly enhance our understanding of the mechanisms by which glia promote nervous system dysfunction in AxD specifically, and in neurological diseases more generally.